Muffle furnace leer



Aug. 9, 1932. w. A. MoRToN MUFFLE FURNACE LEER Filed Feb. 8, 1929 NN.ON.

Patented Aug. 9, 1932 UNITED STATES PATENT OFFICE MUFFLE FURNACE LEERApplication filed February 8, 1929. Serial No. 388,464.

This invention relates to mue furnace structures, more particularly tofurnaces of the tunnel type for use as annealing leers in the treatmentof glassware. It is a special object of the present invention to providetemperature regulation in leers for annealing glassware taken fromware-forming machines, the apparatus designed for this purpose beingparticularly adapted to establish and maintain the proper temperatureregulation throughout the length of the leer whereby the ware isinitially treated at red heat, and passed out of the leer atsubstantially atmospheric or room temperature.

Annealing leers are commonly constructed with muflie hearth having aflue extending therebeneath, it being customary to draw the products ofcombustion from the combustion chamber through the flue along the hearthby a forced draft.

It has been attempted to produce draft regulation in the furnace chamberby breaking up the flue in separate heating zones which areindependently regulated to vary the temperature in the chamber. Inaccordance with the present invention it is proposed to utilize anuninterrupted flue passage leading from the combustion chamber and toeffect the necessary temperature regulation within the heating chamberper se.

In an annealing leer heat will radiate from the mule hearth to theinterior of the annealing chamber, and it is proposed to provide asimple regulating means in the form of variable resistance to theradiation of heat for controlling the heatihg temperature, pre ferablyby a single adjustment and simultaneously extending the length of thefirst heating zone in the chamber, the regulating means eing a series oflouvers which are controlled exteriorly of the furnace to vary thespacing therebetween.

Glass is annealed by means of several distinct heating cycles, theinitial of which is usually termed the heat soaking zone Where the massis brought to a uniform temperature diminishing very slowly and thensubsequently accelerated. The length of this soaking period isdetermined by the glass thickness or general character.

A certain initial temperature may be produced with a given heat supplyrate with the louvers open and the lower hearth having a conductivityrate which would diminish its surface temperature rapidly within thelimits of the superimposed'louvers; similarly, the

same initial temperature may prevail with y shutters to regulate theescape of heat through` the furnace wall. These and other features, suchas varying the degree of insulation by adjusting the divided wall, whichmay be of composite materials, will become more apparent from aconsideration of the accompanying drawing, in which like referencecharacters designate like parts and in which Fig. l is a Sectionalelevational view of an annealing leer for glassware, embodying theprinciples of this invention; Fig. 2 is a transverse sectional viewthereof taken along the line I`II, Fig. 1 and Fig. 3 is an enlargeddetail View of one end of the leer illustrating the actuating mechanismfor the louvers.

Referring to the several figures of the drawing, the structure thereinillustrated comprises a tunnel-forming wall structure having top andbottom Walls, 1 and 2, and side walls 3, portions of which-areconstructed of refractory or other heat insulating material. At one endof the furnace this bottom wall 2 is offset to form a combustion chamber4 having a communicating flue 5 the extended end of which is connectedto a conduit 6 leading to a fan blower 7 which exhausts the conduit toset up a forced draft or suction, whereby the products of combustionfrom the chamber 4 are drawn through the flue. A hearth 8 of refractorytile 9 or heat-resisting alloy sect-ions, is constructed to extend thelength of the combustion chamber and flue 4 ing in the high temperaturezone o nace and forming a heating chamber above is necessarily and 5respectively. This hearth element bef the furthe combustion chamber andflue.

A wire mesh endless conveyor belt 10 is disposed to operatelongitudinally within the furnace chamber, this conveyor being suspendedon roller supports 11 and extending from an end roller 12 at thecharging end of the leer to a main drive roller 13 at the delivery endof the leer, the roll 13 being operated through a geared transmission 14and drive motor 15. i

The conveyor belt is maintained under suitable tension by an adjustingroll 16 and a weighted roll 17 the latter maintaining tension on thebelt by action of gravity. Disposed between the conveyor belt 10 and thehearth 8 are a plurality of louvers 20 which are pivotally mounted inthe side walls of the furnace, by means of shafts 21, as clearly shownin Fig.'2. The louvers are in the form of double winged baflles having acentral perforation for receiving the pivot shafts 21, and they are ofsuch width that when assembled' in spaced relation in the manner shownin Fig. 3 they form a substantially closed hearth element in spacedrelation with the hearth 9. The shafts are designed to project beyondthe side wall 3 at one end and are provided with links or cranks 22 bymeans of which they are attached to the operating bar 23. By moving thebar 23 all ofthelouvers are'simultaneously pivoted to vary the open-ving of the spaces therebetween in the manner illustrated in Fig. 1.

At the low temperature end of the tunnel the roof, as illustrated inFig. 1, is of a reduced wall section, and is provided with heatradiating means' in the form of shutters 25 and hinged insulatingmembers 24; which are supported in various positions radiating area atthis portion of the tunnel. Instead of the members 25 the roof may beconstructed of sheet metal to induce heat loss by radiation, and similarprovision may be made on the side wall of the tunnel at this portion ofthe leer.

In the operation of the furnace the louvers 20 are regulated through theoperating bar 23 to control the .heat radiating from the hearth 8 to theinterior of the treating chamber whereby the temperaure in the hot endof the leer can be maintained or varied as desired. Since the hot zoneof the furnace gion of the combustion chamber 4 a temperature variantwill be obtained by virtue of the hearth being hottest at this point,the hearth portion in the region of the iiue being of lesser temperaturethan the portion immediately above the combustion chamber.

On this account the regulation eected by the louvers is in the form of avariable resistance to the radiatiom of heat from the hearth .louversmay.

to vary theymeans adjacent a portion at the charging end in therewhereby a diminishing temperature gradient. and temperature regulationAis adequately ef fective within the heating chamber.

Although the inventionhas been illustrated. as an embodiment ofannealing leers for glassware, it will be employed in other furnacestructures and for purposes other than the treatment of glassware. Thelouvers may be employed in conjunction with electrical resistor furnacesor naces, as may be found convenient.

Although one embodiment of the invention has been herein illustrated anddescribed, it will be obvious to those skilled in the art that variousmodifications may made without departing from the principles herein setforth.

' I claim herein as my invention:

1. An annealing furnace comprising a chamber-forming wall structure,heating means adjacent the bottom wall thereof, louvers disposed withinsaid chamber adjacent said bottom wall and adjusting means for varyingtheV degree of opening between adjacent louvers.

2. An annealing furnace comprising a chamber-forming wall structure,heating means adjacent said wall structure, louvers disposed within saidchamber in longitudinal spaced relation with said wall, and means foradjusting said louvers.

3. An annealing furnace comprising a chamber-forming wall structure,heating means adjacent the bottom wall thereof, louvers disposed withinsaid chamber in longitudinal spaced relation with said bottom wall, andconnecting means joining said louvers and adapted for adjusting thespace between adjacent louvers. l

4. An annealing furnace comprising a chamber-forming wall structure,heating of the bottom wall thereof, baiile members Within said chamberarranged in longitudinal spaced relation with the heated portion of thebottom wall, and means for adjusting said baffles to regulate heatradiation to said chamber.

5. An annealing furnace comprising a chamber-forming wall structure,heating means adjacent a portion of the bottom wall thereof, and avariable resistance element disposed within said chamber and adjacentthe heated portion of said bottom wall for varying the radiation of heatfrom the bottom wall to said chamber.

6. An annealing furnace comprising an annealing chamber, anconveyormounted in said chamber, a heating wall on one side of said chamber, awall disposed between said heating wall and said conveyor comprising a.y

be evident that the regulatingy with gas or oil-burning furpluralityofmovable sections, and means for means adjacent s, wall thereof, andmeans within said chamber for regulating the amount of heat radiatingfrom said wall to said chamber.

" 8. In a furnace requiring a process temperature gradient, thecombination of a plurality of superposed bottom walls in the heatlngzone, one of which being movable whereby the heating is variable, and a.Elm

l0 rality of 1a ers of msulation in the vcoo zone one o which is movablewhereby the cooling is variable. Y

In testimony whereof I have hereunto set my hand this 7 day of February,1929, at

Pittsburgh, Pa. A

WILLIAM A. MORTON.

